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# Copyright (C) 2005 Canonical Ltd
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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# Author: Martin Pool <mbp@canonical.com>
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"""Weave - storage of related text file versions"""
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# TODO: Perhaps have copy and comparison methods of Weave instances?
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class VerInfo(object):
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"""Information about a version in a Weave."""
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included = frozenset()
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def __init__(self, included=None):
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self.included = frozenset(included)
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s = self.__class__.__name__ + '('
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s += 'included=%r' % (list(self.included))
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"""weave - versioned text file storage.
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A Weave manages versions of line-based text files, keeping track of the
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originating version for each line.
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Texts can be identified in either of two ways:
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* a nonnegative index number.
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* a version-id string.
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Typically the index number will be valid only inside this weave and
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the version-id is used to reference it in the larger world.
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The weave is represented as a list mixing edit instructions and
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literal text. Each entry in _l can be either a string (or
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unicode), or a tuple. If a string, it means that the given line
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should be output in the currently active revisions.
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If a tuple, it gives a processing instruction saying in which
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revisions the enclosed lines are active. The tuple has the form
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(instruction, version).
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The instruction can be '{' or '}' for an insertion block, and '['
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and ']' for a deletion block respectively. The version is the
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integer version index.
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* A later version can delete lines that were introduced by any
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number of ancestor versions; this implies that deletion
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instructions can span insertion blocks without regard to the
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insertion block's nesting.
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* Similarly, deletions need not be properly nested with regard to
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each other, because they might have been generated by
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independent revisions.
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* It doesn't seem very useful to have an active insertion
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inside an inactive insertion, but it might happen.
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* Therefore, all instructions are always"considered"; that
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is passed onto and off the stack. An outer inactive block
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doesn't disable an inner block.
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* Lines are enabled if the most recent enclosing insertion is
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active and none of the enclosing deletions are active.
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List of versions, indexed by index number.
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For each version we store the tuple (included_versions), which
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lists the previous versions also considered active.
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def add(self, parents, text):
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"""Add a single text on top of the weave.
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Returns the index number of the newly added version.
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List or set of parent version numbers.
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Sequence of lines to be added in the new version."""
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self._check_versions(parents)
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self._check_lines(text)
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parents = frozenset(parents)
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delta = self._delta(parents, text)
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# offset gives the number of lines that have been inserted
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# into the weave up to the current point; if the original edit instruction
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# says to change line A then we actually change (A+offset)
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for i1, i2, newlines in delta:
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assert i2 <= len(self._l)
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raise NotImplementedError("can't handle replacing weave [%d:%d] yet"
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self._l.insert(i1 + offset, ('{', idx))
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self._l[i:i] = newlines
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self._l.insert(i + 1, ('}', idx))
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offset += 2 + len(newlines)
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self._v.append(VerInfo(parents))
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# special case; adding with no parents revision; can do this
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# more quickly by just appending unconditionally
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self._l.append(('{', idx))
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self._l.append(('}', idx))
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self._v.append(VerInfo())
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def _check_lines(self, text):
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if not isinstance(text, list):
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raise ValueError("text should be a list, not %s" % type(text))
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if not isinstance(l, basestring):
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raise ValueError("text line should be a string or unicode, not %s" % type(l))
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def _check_versions(self, indexes):
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"""Check everything in the sequence of indexes is valid"""
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raise IndexError("invalid version number %r" % i)
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def annotate(self, index):
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return list(self.annotate_iter(index))
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def annotate_iter(self, index):
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"""Yield list of (index-id, line) pairs for the specified version.
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The index indicates when the line originated in the weave."""
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raise IndexError('version index %d out of range' % index)
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included = set(vi.included)
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for origin, lineno, text in self._extract(included):
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def _extract(self, included):
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"""Yield annotation of lines in included set.
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Yields a sequence of tuples (origin, lineno, text), where
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origin is the origin version, lineno the index in the weave,
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and text the text of the line.
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The set typically but not necessarily corresponds to a version.
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if isinstance(l, tuple):
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isactive = (v in included)
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oldc, oldv = stack.pop()
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isactive = stack and (stack[-1][1] in included)
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raise ValueError("invalid processing instruction %r on line %d"
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assert isinstance(l, basestring)
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raise ValueError("literal at top level on line %d"
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origin = stack[-1][1]
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yield origin, lineno, l
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raise ValueError("unclosed blocks at end of weave",
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def getiter(self, index):
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"""Yield lines for the specified version."""
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for origin, line in self.annotate_iter(index):
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def get(self, index):
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return list(self.getiter(index))
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def dump(self, to_file):
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from pprint import pprint
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print >>to_file, "Weave._l = ",
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pprint(self._l, to_file)
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print >>to_file, "Weave._v = ",
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pprint(self._v, to_file)
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for vers_info in self._v:
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for vi in vers_info[0]:
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if vi < 0 or vi >= index:
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raise ValueError("invalid included version %d for index %d"
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raise ValueError("repeated included version %d for index %d"
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def _delta(self, included, lines):
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"""Return changes from basis to new revision.
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The old text for comparison is the union of included revisions.
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This is used in inserting a new text.
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Delta is returned as a sequence of (line1, line2, newlines),
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indicating that line1 through line2 of the old weave should be
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replaced by the sequence of lines in newlines. Note that
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these line numbers are positions in the total weave and don't
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correspond to the lines in any extracted version, or even the
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extracted union of included versions.
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If line1=line2, this is a pure insert; if newlines=[] this is a
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pure delete. (Similar to difflib.)
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self._check_versions(included)
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##from pprint import pprint
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# first get basis for comparison
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# basis holds (lineno, origin, line)
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basis = list(self._extract(included))
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# now make a parallel list with only the text, to pass to the differ
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basis_lines = [line for (origin, lineno, line) in basis]
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# add a sentinal, because we can also match against the final line
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basis.append((len(self._l), None))
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# XXX: which line of the weave should we really consider matches the end of the file?
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# the current code says it's the last line of the weave?
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from difflib import SequenceMatcher
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s = SequenceMatcher(None, basis_lines, lines)
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##print 'basis sequence:'
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for tag, i1, i2, j1, j2 in s.get_opcodes():
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##print tag, i1, i2, j1, j2
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# i1,i2 are given in offsets within basis_lines; we need to map them
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# back to offsets within the entire weave
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real_i1 = basis[i1][0]
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real_i2 = basis[i2][0]
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assert j2 <= len(lines)
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yield real_i1, real_i2, lines[j1:j2]
added
removed
weave.py
